Telephone switch-board



VT. DE LooKWooD. TelephoneSWto'h Board.

Patented March 1,1881.

(No Model.)

UNITED STATES .PATENT Carica.

THOMAS DE LOCKWOOD, OF MALDEN, ASSIGNOR TO AMERICAN BELLTELE- PHONECOMPANY, OF BOSTON, MASSACHUSETTS.

TELEPHONE SWITCH-BOARD.

SPECIFICATION forming part of Letters Patent No. 238,217, dated March 1,1881.

- Application tiled August 21, 1880. (No model.)

To'all whom it mafy concern:

Be it known that I, THOMAS DE LocKwooD, of Malden, in the county ofMiddlesex and State of Massachusetts, have invented certain Improvementsin Telephone Switch-Boards, of

which the following is a specification.

This invention relates to that class of telephone central-oiiceswitch-boards which are composed of a series of metallic strips, each ioconnected to or forming a part of one of the line-circuits, and a seriesot' connecting-strips arranged substantially at right angles to theline-circuit strips and normally disconnected from the latter, eachconnecting-strip being insulated from the others and adapted to connectany two of the line-circuit strips when engaged therewith by suitableplugs or other connecting devices.

Heretofore both the line-circuit strips and l zo the connecting-stripshave been rigid and have been rigidly attached to a suitable board orframe, the line-circuit strips being in front of but not in contact withthe connecting-strips, and provided with sliding or other plugs, z5whereby each line-circuit strip can be connected with either of theconnecting-strips. The network ot' strips involved by this constructionis somewhat confusing, .so-that mistakes are liable to be made in makingthe de- 3o sired connections.

My invention has for its object, mainly, to obviate such confusion in aswitch-board of the class above mentioned; and to this end it consistsin the substitution, for the rigid line- 3 5 circuit strips heretoforeused, of liexible strips, each supported at a point above the front ofthe switch-board, and permanently connected with or forming part of theline-circuits, and provided with a spring-impelled drum where- 4o byitis automatically removed from the front of the switch-board, and witha plug or device whereby it may be connected to either of theconnecting-strips.

My invention also consists in certain other improvements relating toswitch-boards and central-office systems, all of which I will nowproceed to describe and claim.

Of the accompanying drawings, forming a part of this specification,Figure 1 shows a dia- 5o grammicsectional view of an arrangement of myinvention. Fig. 2 represents a front view ot' the switch-board, with theannunciators and spring-retracting flexible connecting bands or tapes inposition. Fig. 3 represents an enlarged section of the switch-plug. Fig.4 rep- 55 resents an enlarged section on line mx, Fig. 1.

Like parts in all the figures are correspondingly designated.

In the drawings, A represents a switchboard composed ot' the usualbacking of wood 6o or other insulating material, and provided with theusual rigid metallic connecting-strips c, and with line-circuit stripst, arranged substantially at right angles to the connectingstrips whenin operative position. The connecting-strips a are rigidly attached tothe board A, as usual; but the line-circuit strips, instead of beingrigid, are composed of flexible metal tapes, each secured at one end toa rotary metallic drum, c, located above the 7o strips a and providedwith a spring, s, arranged on a spindle and adapted to rotate the drumc, so as to wind up the tape or strip attached to it automatically, theoperation of each drum and its spring being similar to that ot' anordinary spring tape-measure, so that the strips t are normally woundupon the drums c, and thus elevated above the strips a. Each drum c isinclosed by a metallic casing, F, of

any suitable form adapted to cover the coiled 8o I portions of the stript, and each casingis provided with a guard, c', to limit the upwardmovement ot the strip tu Each strip tis electrically connected to itsline-circuit, as is usual in switch-boards of this class, the connectionbeing through the drum c, the arbor on which said drum rotates and thespring s, as shown in Fig. l, the drum and spring performing the twofoldfunction of automatically withdrawing the strip from the front of theswitch- 9o board and connecting it to the line circuit. Each strip t isadapted to be secured toeither of the connecting-strips a, and to thisend I prefer to provide the strips a with outwardlyprojecting pins b,arranged in Vertical rows in line with the strips t, and provide thestrips t with plugs P, each having a socket adapted to cover one ot' thepins b. Each plug'P is composed of a cylindrical piece hollow at one endto form the socket, and turned down at roo to the wire fw bya spring, t,

the other end to form a shoulder, e', and a screw, e2. A hole is drilledor punched in the outer end of the strip t, through which the screw e2is passed, said strip being clamped against the shoulder c by a nut, n.The outer end of the plug is provided with a handle, e3. The plugs'Pnormally rest upon the projectv ing pins p of the upper metal strip, a,which is the ground-strip, and always has a groundconnection.

By the employment of the flexible line-circuit strips and the means forautomatically elevating the same I avoid the complication and confusionresulting from the employment of the crossed rigid strips and theirconnecting slides, plugs, or springs heretofore used, each line-circuitstrip bein g removed from the face of the switch-board when not in use,and being adapted for use by simply pulling down its plug l? to thedesired point. The strips t are so located in such relation to theswitchboard that when said strips are drawn down they will not touch oneanother; hence all crossing contacts are avoided. If desired,- however,the strips may be suitablyinsulated.

B represents a circular switch arranged upon a base-board, which ispreferably secured to an operators table attached to and immediately infront of thevswitch-board.

d represents the metal lever ot' the switch,

pivoted at f to swing freely in both directions.

7L represents a hack limit or stop-bar for the lever d, said bar beingof annular form, concentric with the pivotf, and supported above thebase-board by studs h h in such manner that the lever d can be swungfreely under it and bear against its under surface when not pressed awayfrom it. rlhe lever d may be held normally against the bar 71l by itsown resilience or by a suitable spring.

The switch is employedwith any convenient number of circuits, six beingshown in the present instance. Each circuit is composed of aline-wircentering the office through one of the usual annunciators D, awire, w', connecting the annunciator to a contact or. button g on theswitch-board, a wire, o, normally connected and extending to one of thestrips t, through the drums c and spring s, as described, and a wire, m,connecting the wire w to a button, gli, for a purpose hereinafterdescribed. In each circuit is a pin-button, j, interposed between thespring t' and the under side of the lever d. When the lever d is in itsnormal position the spring t connects the button g and plate 7c, butwhen the lever d is depressed the pin-button j separates the spring ilfrom the plate 7c, as shown in Fig. 4. The plate 7s of each circuit isconnected to the inner end of one of the strips t by a wire, o, so thatthe depression of the lever d over either of the pin-buttons j cuts outthe strip t to which the plate 7c of the same circuit is connected. rlhepivoted end of the lever d is connected to the switch S by wire fr, asshown, and by means of button 1 of said switch the telephone andtransmitter are putonto the line, by button 2 the battery and calling-keys are switched in, and by means of loutton 3 the magneto-generatoris put to line.

Operation: Suppose a call to come into the office by line w', enteringthrough the first circuit. The operator, noticing the fall of theannunciator, turns the lever d to button g of the rst circuit, pressesit down and makes contact with said button, and at the same timedepresses the spring t' away from plate lc, and turning switch S tobutton l, puts the telephone and transmitter into line, thus making acircuit from line first, annunciator, wire fw', button g, lever d,transmitter, and telephone to ground, and ascertains the wants of thecalling party. Suppose the line entering through the fourth circuit iswanted by said party. The operator then turns lever d to button g of thefourth circuit, depresses the lever to make contact with the saidbutton, at the same time cutting out plate k of said circuit, turns theswitch S to button 2, if a battery-circuit, or to button 3, if amagneto-circuit, using` the calling-keys K in the rst instance, and theniagneto-generator in the last instance, to call up the desired party.When said party has been called the operator draws down the line-circuitstrip t of the first circuit by means of the knob or handle of plug P,and pushes the plug onto the pin b, as shown,of aconnecting-strip a, notin use, directly under said tape-say the fourth strip from the top-thendraws down the strip t of the fourth circuit, places the plug on the pinon the fourth connecting-strip, and turns his lever to the button g ofthe fourth circuit, and turns the switch S to button 1. The twosubscribers are thus placed in communication with each other, and theoperators telephone is in circuit, so that he can learn whether they aretalking or not. When the lever d is pressed upon button g of the fourthcircuit, which is electrically connected to button gf of the sannecircuit by wire m, the telephone and transmitter are putin abranchcircuit, so that the operator can hear, as described. Gonnections arethus made with any two circuits or lines in the least possible time andwith the greatest ease and simplicity.y

By the employment of the hollow plug a much longer bearing can beobtained than bythe ordinary solid or split plug inserted into a hole inthe connecting-strip, and the wear resulting from frequent use ismaterially decreased, there being no necessity of a tight t of the plugon the pin, as the retractile power of the spring tends to draw the plugupward when placed on a pin, thus holding the plug against the pin witha yielding pressure, and securing perfect electrical contact with thesame.

The employment of the pin-button j, interposed between the lever d andsprings z', enables either of the line-circuits to be cut out from itsground connection by the same operation that connects such line-circuitwith the IOO IIO

IZO

central office. rJhis feature enhances the rapidity of operation, and Ibelieve it to be novel.

A switch, arranged to swing freely in either direction, also adds to thequickness of operation as Well as simplicity of construction.

There may be as many circuits on a single circular switch as can beconveniently worked by one operator.

I am aware that it is not new to combine With the terminal of aline anextension-cord or Vswitch-connection, having an automatic takeup orspring-impelled drum; but I am not aware that a series ofliexiblelinecircuit strips, provided with springimpelled drums, andpermanently connected with and forming parts of the line-circuits, haveever been employed in combination with connectingst1ips,as hereindescribed, the springimpelled drums baving the two-fold function beforenamed.

I claiml. In a switch-board of the class herein described, thecombination, with the xed connecting-strips a, of the flexible suspendedstrips t, permanently connected With or forming parts of theline-circuits, each strip t being provided with a spring-impelled drum,whereby it is automatically removed from the front of the switch-board,and with a plug or device whereby it may be connected to either of theconnecting-strips a, as set forth.

2. The flexible metallic strip t, combined with the metallic spring-drumF, lits arbor,

aline-circuit, and a ground-switch, substan line-circuits and arrangedin circular order,

a spring switch-lever, pivoted at a point practically equidistan't fromthe buttons or contacts, adapted to make contact with either of the sameand normally disconnected from the buttons7 and an annular barconcentric With the pivots of the lever and adapted to serve as a backstop for the same in any of the positions in which it may be placed,substantially as described.

4. In a central-office telephone system, comprising wires w and o,springs i, plates k, and buttons g and ga, the lever d and pins j,adapt-l ed, by depression, to connect the line-circuit entering at eachot' said buttons with the central-ofce telephone and transmitter, and atthe same time and by the same movement to cutout the previousearth-connection of the same linecircuit, substantially as described.

In testimony WhereofI have signed my name to this specication, in thepresence of two subscribing Witnesses, this 19th day of August.

T. DE LOOKWOOD.

Witnesses:

W. C. ToMPKINs, GEO. W. PIERCE.

